Procedure for Material Failure Characterization through GISSMO 2019-26-0284

Vehicle crashworthiness is an important aspect of vehicle development. Vehicle structural performance plays a critical role during crash for controlling the occupant injuries. During a crash event, vehicle energy management governs the structural performance and passenger compartment integrity. However, these parameters are dependent on material properties such as yield/ultimate tensile strength, work hardening effects, strain rate dependency, material elongations and material fracture strains. Appropriate representation of these material properties in CAE (Computer Aided Engineering) environment is very critical for reliable prediction of vehicle structural performance during development phase. Among all material properties, material fracture strain is the most complex one and needs detailed material characterization approach for failure definitions.

Conventional approach for material failure prediction is based on failure strain obtained through uniaxial tensile test as per ASTM E8 standard. This approach however limits ability to predict failure under dynamic loading conditions wherein material experiences variable state of stress (non-proportional loading) like combination of tensile, shear and compressive loading in considerably shorter period of time. This limitation of conventional failure prediction approach is effectively addressed through GISSMO, which inherently accommodates effect of variable state of stress continuously during dynamic loading conditions; making it suitable for crash simulations.

This work includes GISSMO material model development process; which involves coupon testing under different types of loading, corresponding CAE analysis, development of failure curve, element size and strain rate regularization. This work is explained through example of dual phase steel DP590.